The overall objective of this project is to study interphase chromosomes in the form of prematurely condensed chromosomes (PCC) and ultimately relate the composition to genetic inheritance and the process of oncogenesis. In order to fulfill this objective we will: 1) isolate and purify PCC from sequential stages in the cell cycle; 2) correlate morphological and ultrastructural relationships of the PCC throughout the cell cycle; 3) gain insights into chromosome architecture by examination of PCC by high resolution microscopy; 4) biochemically analyze isolated PCC to determine nonhistone proteins which have a transient involvement with the interphase chromosome; 5) determine the protein(s) which are responsible for chromosome condensation; 6) and localize specific nonhistone proteins of interest on PCC and metaphase chromosomes. The information from the proposed studies will provide a baseline of biochemical information for future studies directed toward the effects of carcinogenic and chemotherapeutic agents on the genetic material.